As early as 1822, the postmaster in Washington, D.C. was worried by the amount of extra mail at Christmas time. His preferred solution to the problem was to limit by law the number of cards a person could send. Even though commercial cards were not available at that time, people were already sending so many home-made cards. How many more extra postmen had to be hired in the city?

"That year, the Superintendent of
Mails in Washington, D.C., complained of the need to hire sixteen extra
mailmen. Fearful of future bottlenecks, he petitioned Congress to limit
the exchange of cards by post, concluding, "I don't know what we'll do if it keeps on."


here

Yes Jenny. "16" is right. Thanx Also